What’s a big sister to do?

Throughout the pregnancy, we have been very open with our oldest daughter that is three and a half years old. While we were planning our birth at the Birthing Center she went with us to all of our appointments. She has watched numerous birthing videos with me, real birthing videos, not ones that have been edited for TV. She knew about normal birth, and how the baby grows inside her mommy. She had been planning on cutting the cord of her younger sister and was telling everyone about it. Now plans had changed a bit due to the diagnoses of Hydrocephalus and Dandy-Walker of our unborn baby girl.
We now keep her involved in the pregnancy, but she doesn’t go with us to our appointments at the Perinatal Center. She was with us for the original ultrasound where we learned of the Hydrocephalus. The appointments are quite stressful, so we make the day fun for her by taking her to spend the day with my parents. This gives my husband and I the time to go to the appointments together, and then regroup deal with the latest news before going back to pick her up. It works well for all of us.
We still keep our daughter informed on the pregnancy, but on her level. She knows she is going to be a big sister, but now we’re not going to have a water birth. She also knows the baby is a bit sick and will need to be in the hospital. We try not to focus so much on the negative, but also want her to be aware of the changes that we’re all going to experience in the upcoming months.
At this weeks appointment we were hoping to still have stable measurements, but we had no such luck. So that was quite disappointing. We’re about 31 weeks pregnant and her head circumference is 311mm, or about 35 weeks. Her body is only measuring at about 26 weeks. At this point I’m still hoping for a vaginal delivery, though it is looking less and less likely.